CPU (Central Processing Unit) MCQs Quiz | Class 9
This quiz is for Class 9 students studying Computer Applications (Code 165), based on Unit 1: Basics of Information Technology. It specifically covers the topic of the CPU (Central Processing Unit), including its role, processing functions, control mechanisms, and the basic internal parts like the Control Unit (CU) and Arithmetic Logic Unit (ALU). Attempt all questions and click “Submit Quiz” to see your score and download a PDF of your answers.
Understanding the CPU (Central Processing Unit)
The Central Processing Unit (CPU) is often called the “brain” of the computer. It is the most important component, responsible for executing instructions and performing calculations that allow your computer to run. Without a CPU, a computer cannot function. It handles all the commands it receives from the hardware and software running on the computer.
The Role and Function of the CPU
The primary job of the CPU is to process instructions. This involves three main steps, often called the instruction cycle:
- Fetch: The CPU retrieves instructions from the computer’s memory (RAM).
- Decode: The CPU interprets or “decodes” what the instruction means.
- Execute: The CPU performs the action required by the instruction. This could be a mathematical calculation, moving data, or making a decision.
This cycle happens millions or even billions of times per second, which is why computer processors are measured in Gigahertz (GHz).
Basic Internal Parts of the CPU
The CPU is made up of two main components that work together to process information:
1. Control Unit (CU)
The Control Unit acts like a traffic manager or a director. It doesn’t perform any actual processing but instead manages and coordinates all the activities inside the computer. It tells the computer’s memory, the ALU, and input/output devices how to respond to the instructions that have been sent to the processor. It controls the flow of data within the CPU.
2. Arithmetic Logic Unit (ALU)
The Arithmetic Logic Unit is where the real “thinking” or calculation happens. It has two main functions:
- Arithmetic Operations: It performs all mathematical calculations like addition, subtraction, multiplication, and division.
- Logical Operations: It handles logical decisions by comparing data. For example, it can determine if one number is greater than, less than, or equal to another number.
| Component | Primary Function | Example of Operations |
|---|---|---|
| Control Unit (CU) | Directs and coordinates operations | Fetching instructions, controlling data flow |
| Arithmetic Logic Unit (ALU) | Performs calculations and comparisons | 5 + 3, Check if X > Y |
Quick Revision Points
- CPU: Central Processing Unit, the brain of the computer.
- Processing: The act of executing instructions.
- Instruction Cycle: The Fetch-Decode-Execute sequence.
- Control Unit (CU): Manages the flow of data and instructions.
- Arithmetic Logic Unit (ALU): Performs all math and logic operations.
- Processor Speed: Measured in Hertz (Hz), commonly Gigahertz (GHz).
Extra Practice Questions
- What is the full form of ALU and what are its two main types of operations?
- Explain the Fetch-Decode-Execute cycle in your own words.
- If the CPU is the “brain”, what role does the Control Unit play?
- Why is the CPU essential for a computer to work?
- Give an example of a logical operation that the ALU might perform.
